linux-kernel - 回复: [PATCH] mm: vmscan: export func:shrink

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Date:   Tue, 20 Jun 2023 03:05:27 +0000
From:   李培锋(wink) <lipeifeng@...o.com>
To:     David Hildenbrand <david@...hat.com>,
        "akpm@...ux-foundation.org" <akpm@...ux-foundation.org>
CC:     "linux-mm@...ck.org" <linux-mm@...ck.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "surenb@...gle.com" <surenb@...gle.com>,
        "gregkh@...gle.com" <gregkh@...gle.com>,
        "zhangshiming@....com" <zhangshiming@....com>,
        郭健 <guojian@...o.com>
Subject: 回复: [PATCH] mm: vmscan: export func:shrink_slab

On 16.06.23 11:21, lipeifeng@...o.com wrote:
>> From: lipeifeng <lipeifeng@...o.com>
>> 
>> Some of shrinkers during shrink_slab would enter synchronous-wait due 
>> to lock or other reasons, which would causes kswapd or direct_reclaim 
>> to be blocked.
>> 
>> This patch export shrink_slab so that it can be called in drivers 
>> which can shrink memory independently.
>> 
>> Signed-off-by: lipeifeng <lipeifeng@...o.com>
>> ---
>>   mm/vmscan.c | 3 ++-
>>   1 file changed, 2 insertions(+), 1 deletion(-)
>> 
>> diff --git a/mm/vmscan.c b/mm/vmscan.c index 
>> 6d0cd2840cf0..2e54fa52e7ec 100644
>> --- a/mm/vmscan.c
>> +++ b/mm/vmscan.c
>> @@ -1043,7 +1043,7 @@ static unsigned long shrink_slab_memcg(gfp_t gfp_mask, int nid,
>>    *
>>    * Returns the number of reclaimed slab objects.
>>    */
>> -static unsigned long shrink_slab(gfp_t gfp_mask, int nid,
>> +unsigned long shrink_slab(gfp_t gfp_mask, int nid,
>>   				 struct mem_cgroup *memcg,
>>   				 int priority)
>>   {
>> @@ -1087,6 +1087,7 @@ static unsigned long shrink_slab(gfp_t gfp_mask, int nid,
>>   	cond_resched();
>>   	return freed;
>>   }
>> +EXPORT_SYMBOL_GPL(shrink_slab);
>>   
>>   static unsigned long drop_slab_node(int nid)
>>   {
>
>It feels like something we don't want arbitrary drivers to call.
>
>Unrelated to that, this better be sent along with actual driver usage.

Hi Sir：

Virtually, we have implemented async shrink_slabd isolated from kswapd and direct_reclaim.
The goal above it is to avoid the sync-wait in kswapd or direct_reclaim due to some shrinkers.

But the async shrink_slabd was only applied to mobile products so that I didn't make sure any
risk in other products. For the above reasons, I wanna merge the patch to export shrink_slab
and the patch of drivers would be considered to be pushed if I check all the risks.

Some informal code files of driver are attached for your reference.

-----邮件原件-----
发件人: David Hildenbrand <david@...hat.com> 
发送时间: 2023年6月16日 17:43
收件人: 李培锋(wink) <lipeifeng@...o.com>; akpm@...ux-foundation.org
抄送: linux-mm@...ck.org; linux-kernel@...r.kernel.org; surenb@...gle.com; gregkh@...gle.com
主题: Re: [PATCH] mm: vmscan: export func:shrink_slab

On 16.06.23 11:21, lipeifeng@...o.com wrote:
> From: lipeifeng <lipeifeng@...o.com>
> 
> Some of shrinkers during shrink_slab would enter synchronous-wait due 
> to lock or other reasons, which would causes kswapd or direct_reclaim 
> to be blocked.
> 
> This patch export shrink_slab so that it can be called in drivers 
> which can shrink memory independently.
> 
> Signed-off-by: lipeifeng <lipeifeng@...o.com>
> ---
>   mm/vmscan.c | 3 ++-
>   1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/mm/vmscan.c b/mm/vmscan.c index 
> 6d0cd2840cf0..2e54fa52e7ec 100644
> --- a/mm/vmscan.c
> +++ b/mm/vmscan.c
> @@ -1043,7 +1043,7 @@ static unsigned long shrink_slab_memcg(gfp_t gfp_mask, int nid,
>    *
>    * Returns the number of reclaimed slab objects.
>    */
> -static unsigned long shrink_slab(gfp_t gfp_mask, int nid,
> +unsigned long shrink_slab(gfp_t gfp_mask, int nid,
>   				 struct mem_cgroup *memcg,
>   				 int priority)
>   {
> @@ -1087,6 +1087,7 @@ static unsigned long shrink_slab(gfp_t gfp_mask, int nid,
>   	cond_resched();
>   	return freed;
>   }
> +EXPORT_SYMBOL_GPL(shrink_slab);
>   
>   static unsigned long drop_slab_node(int nid)
>   {

It feels like something we don't want arbitrary drivers to call.

Unrelated to that, this better be sent along with actual driver usage.

--
Cheers,

David / dhildenb


View attachment "kshrink_slabd.c" of type "text/plain" (5448 bytes)